This was a cross-sectional descriptive research, aimed to investigate the health literacy issues and factors related to health literacy of public health students at the Praboromarajchanok Institute, Ministry of Public Health, Thailand. The study included 143 students (final year) of the Bachelor of Public Health degree in the Community Health Program. Students who were unwilling to participate in the research project were excluded. This research has been considered by the Human Research Ethics Committee of Mahasarakham University with the Approval number: 086/2019 to protect participant rights, so that the participant has the right to withdraw from the program throughout the duration of the study.

A questionnaire (144 item) was developed by the researchers, with three sections dealing with background demographic data (9 items), critical thinking (15 items), and health literacy (120 items). [ANNEXURE I] (available as Supplemental data). The Critical section contained multiple choice with a score of 1 for each correct answer. The scores were divided into 3 levels [12]: low level (less than 60 per cent of total points), moderate level (60-79 per cent of total points), and high level (80 and above per cent of total points). The health literacy section employed 5 rating scales questions to establish the performance level. The scores were again divided into 3 levels [13]: low level (range 1.00-2.33 points), moderate level (range 2.34-3.67 points), and high level (range 3.68-5.00 points). The factors that related to health literacy were categorised into 2 groups (dichotomous variables), in problem solving and promoting health literacy, which was to set the code 0 as a reference group, including: Health literacy [14] (High=1, Moderate and Low=0) Critical thinking (High=1, Moderate and Low=0) Gender (Male=1, Female=0) Age (23 years=1, <23 years=0) Income (enough for spending=1 not enough to spend,=0) Feelings about current health (good and very good=1, inadequate=0) GPA (3.00=1, <3.00=0) [15].

The content of the health literacy questionnaire was validated by 3 experts analysing by the index of Item-Objective Congruence (IOC), who found that every item had an IOC of 0.50-1.00 [16,17]. Then, it was tried out with 20 Bachelor of Public Health students in Community Health, College of Public Health, Sirindhorn, Yala Province, specifying Cronbach’s alpha at null hypothesis (CA0)=0 and expected value of Cronbach’s alpha (CA1)=0.7, α=0.05, Power (1-β)=0.1 [18]. The sections of the questionnaire on critical thinking and health literacy were found to have a reliability of 0.75 and 0.96, respectively.

Data were analysed by SPSS for Windows Version 18 under license of Mahasarakham University. The descriptive statistics for sequence variables were established as mean and standard error, while categorical variables were depicted as frequencies with percentages for the whole sample. Inferential statistics were used with multiple logistics regression to analyse the factors related to health literacy, presenting the adjusted odds ratio with a 95% Confidence Interval (CI) and p-value. p-value less than 0.05 was considered as statistically significant.

It was found that 34 (23.77%) of the participants were from Suphan Buri Province. 109 (76.22%) of the respondents were female, and 133 (93.01%) were single marital status. The average age was 23.39±4.15 years. 57(39.86%) had a GPA of 3.00 and above, average income received for expenses was 5,339.15±2,300.89 baht per month, 105 (73.43%) considered their income to be sufficient, 139 (97.20%) were without chronic diseases, and 104 (72.73%) had good feeling about their health.

Students had an average critical thinking score equal to 9.31±1.99 from a full score of 15, and 81(56.64%) had a moderate level of critical thinking [Table/Fig-1].

Students had the highest mean score for health literacy on disease prevention (3.96±0.57 points), followed by medical care (3.95±0.60 points), and the lowest score was rehabilitation (3.88±0.57 points). The average for health literacy was 3.65±0.46 out of 5 points, as most of students had a high level of health literacy at 78 (54.55 %) [Table/Fig-2].

Analysing factors that were related to health literacy by multivariable analysis, it was found that the factors that were associated with a high level of health literacy with a statistical significance of 0.05, were gender, GPA and critical thinking. In the case of gender, male students had a level of health literacy 3.11 times higher than female (95% CI: 1.28-7.58; p-value= 0.012). Students with a GPA higher than 3.00 had a level of health knowledge 2.41 times that of students with a GPA <3.00 (95% CI:1.15-5.04; p-value=0.019). Students with good critical thinking had a level of health knowledge 2.99 times that of students with low-moderate critical thinking (95% CI: 1.36-6.54; p-value=0.006) [Table/Fig-3].

Health literacy is an intersection of health and education, which involves more than reading ability [19]. It is a necessary skill for people to develop appropriate health behaviour. It is also a special concern for future healthcare professionals, who can provide a healthcare model for patients and even people around them. These results revealed that the health literacy of the students was at a moderate level. The scores were highest in disease prevention, moderate in medical care and lowest in rehabilitation, which was in accordance with the fact that the sample of this study was final year students, who had passed courses such as health promotion, disease prevention, primary therapy, rehabilitation, and consumer protection. The students had also done practical service in the local community and their instructors used a variety of teaching methods to promote students’ 21^st century skills. In addition to the literacy gained in the classroom, students also need to take action, such as searching for information from the college, which provides various resources to help learners learn and practice their skills to gain more information on health care, disease prevention and health promotion. In addition, the topic of health matters is something that students must learn and pay special attention to more than the general public. Students must communicate with clients and provide access to health information that is beneficial to clients [20]. This is consistent with the health education literacy of nursing students which is found at the highest level [6] and, consistent with Naresuan University students with a high level of knowledge of health and good health promoting behaviours [21].

Gender correlated with statistical health literacy significantly, so male students, may have a higher level of health literacy because they have more varied life experiences, may be influenced by peer groups and have better information technology skills than females. This is consistent with another study that have found that gender is related to health literacy [22]. One previous study found that males have better knowledge of health in the component of decision making skills which enhance health behaviours [23]. However, this finding contradicts a study that found that females have a better health literacy than men, with males and females having good health literacy at a level of 52.60% and 60.30%, respectively with a statistical significance (p-value <0.001) [24] whereas some studies found that gender has no relationship with health literacy [25]. GPA correlated with statistical health knowledge significantly because students with very good grades are in a group with a good background and have high intellectual ability. This group of students will learn more and are interested in obtaining new learning and are diligent in pursuing literacy. This is consistent with the study’s findings that the GPA is related to health [25,26].

Critical thinking also has a statistically significant correlation with health literacy. Students with good critical thinking were found to have 2.99 times higher level of health knowledge than students with low-moderate critical thinking. This is due to critical thinking being a thought process that uses reasoning and careful thought when studying data and evidence to consider the reliability of the information, leading to good decision making in understanding what matters should be believed, what should be done, and the reasoning. Thus, critical thinking is associated with health literacy including logical thinking, giving priority to that information that leads to making good decisions [27]. It is consistently found that student’s cognitive ability is related to health literacy in accessing information and health services [28] as well as cognitive impairment being related to reduced health knowledge [29]. There have been studies that have found that abnormal cognition correlates with insufficient statistical health literacy [30].

One important limitation of this study is that it relies on a cross-sectional design that does not permit causal inferences from the observed relationships hence, the findings are provisional ones.

Gender, GPA and student’s critical thinking were found to be associated with high health literacy. Hence, the study can be used as an imperative tool for the stakeholders or policy makers in improving learning of students and encourage them to gain a higher level of health literacy for a sustainable healthcare professional career. Further research including cohort studies have been advised, that are better able to identify causal factors that are associated with health literacy.